Electromagnetically induced transparency and absorption in warm Rb vapor via the Hanle effect: Analysis of observed spectra

We have observed electromagnetically induced transparency (EIT) and electromagnetically induced absorption (EIA) in room temperature Rubidium vapor, by coherent population trapping on the Zeeman substates formed by a magnetic field co-linear with a laser beam passing through the vapor. We have observed EIA on $F_{g} = 3 \rightarrow F'$ transitions in ${}^{85}$Rb and on $F_{g} = 2 \rightarrow F'$ transitions in ${}^{87}$ Rb. We have observed with good signal-to-noise ratio EIT on $F_{g} = 2 \rightarrow F'$ transitions in ${}^{85}$Rb and, for the first time, on $F_{g} = 1 \rightarrow F'$ transitions in ${}^{87}$ Rb. However, certain unexpected features are revealed in the observed spectra, the origins for which remain unclear. We report on our progress toward modelling and understanding the observed EIT and EIA spectra.